Various types of trocars are known that are surgical instruments used to gain access to natural or pathological cavities, to carry out biopsies or to introduce substances, for example to perform intestinal or gynecological celioscopy, or to perform endoscopic operations, in particular arthroscopic operations, by which it is possible to greatly reduce the patient's post-operative recovery period by comparison with procedures involving open surgery. A trocar is generally composed of a hollow tube, also called a cannula or sheath, in which a rod or obturator is able to slide, the distal end of which rod or obturator emerges at the distal end of the tube and is in the form of a tip in order to facilitate penetration into the tissues.
Thus, the patent FR 2,697,150 describes a trocar intended for celioscopy and comprising a tube in which a hollow rod engages which is provided with a tip having recessed facets and capable of containing a device for protecting the tip. The patent application WO 03020140 describes a trocar designed to require only minimal force for insertion into the tissues, so as to reduce as far as possible the damage caused by the penetration, said trocar comprising a tip at the distal end of the obturator, fitting perfectly in the continuation of the distal opening of the cannula, which has a certain degree of flexibility. Such a trocar is intended essentially to be introduced into the soft tissues. Another type of trocar is described in the patent application WO 03045260, according to which a perforating obturator is able to slide in the cannula of the trocar in order to pierce the abdominal wall of a patient during a laparoscopy operation involving introduction of a gas into the abdominal cavity in order to distend it and make the operation easier. However, the trocar according to said document is not designed to perforate a hard wall, such as that of a bone.
Some types of perforating trocars are also known, and are available on the surgical instruments market, which comprise a tip associated with a tube with a cutting distal edge in order to permit penetration into a relatively hard bone, but the effectiveness of trocars of this type is not always satisfactory, particularly in the case of very hard bone resisting conventional cutting tools. Thus, the patent U.S. Pat. No. 5,810,826 describes a perforating trocar comprising a rod with an end in the form of a drill-bit with eccentric tip, guided by a tube. When the rod comes into contact with the bone, its rotation causes the formation of a hole with a diameter wider than that of the rod, by virtue of the off-centered position of the tip, while the tube is held immobile. The use of this trocar is difficult because the operator has to hold the tube with one hand and turn the rod with the other hand.